Method _addExtentElement

src/layer.js:503–508

(mapExtent)

      });
    };
    const _addExtentElement = (mapExtent) => {
      this.whenReady().then(() => {
        delete this._layer.bounds;
        this._validateDisabled();
      });
    };
    // is this really necessary?  Do we believe that remote mapml documents will
    // be interactive i.e. script access to their DOM?
    let root = this.src ? this.shadowRoot : this,